Research On Adaptive Impedance Matching Algorithm For Power Line Carrier Communication

Power line carrier communication(PLC)is a kind of technology which uses power line as the medium to transmit signals.It makes full use of the existing power network resources and realizes the transmission of high frequency signals without affecting the power transmission of power lines.There are many branches of medium-voltage power lines and the operation mode varies greatly,so the impedance at the signal access point is usually unable to match.Therefore,the impedance mismatch is the key point of improving the transmission efficiency of power line communication.The power line carrier communication channel model theory is analyzed at first,and the power line carrier communication channel model of medium voltage is established by using two-port network modeling method.And the channel model is used to analyze the factors which influence the channel impedance.To solve the forbidden zone problem of traditional passive matching network,this paper improves the traditional network structure and combines the partition Smith Circle graph to avoid the forbidden zone.The impedance is calculated by partition and the component parameters of the matching network are calculated quickly and accurately,and the results are verified by simulation.Due to the application of Orthogonal Frequency Division Multiplexing(OFDM),power line carrier communication needs to consider the transmission efficiency within a frequency band rather than a certain frequency point.Therefore,this paper chooses the appropriate matching network considering the actual power line channel model and combining the changes of power line channel impedance in a frequency band,and optimizes the matching network elements with particle swarm optimization(PSO)algorithm to achieve the adaptive impedance matching and optimize the overall matching performance in a frequency band.